Table 1.

Targeted random mutagenesis of the Ser-349/Tyr-365 segment of SecY

Target position	Screening for functional mutations			Screening for dominant-negative mutations
	Number examined	Number of Cs+	Percentage of Cs+	Number examined	Number of Sec−	Percentage of Sec−
Ser-349	58	45	78	282	3	1
Gly-350	42	16	40	340	3	1
Ala-351	28	20	73	298	20	7
Phe-352	64	30	48	358	17	5
Val-353	50	19	38	266	7	3
Pro-354	36	16	44	288	0	0
Gly-355	20	19	95	863	42	5
Ile-356	26	23	88	494	35	7
Arg-357	22	0	0	612	415	68
Pro-358	64	3	5	836	152	18
Gly-359	34	2	6	1,018	111	11
Glu-360	92	57	62	811	5	1
Gln-361	80	24	30	791	7	1
Thr-362	138	31	22	1,171	221	19
Ala-363	239	174	73	355	17	5
Lys-364	33	31	94	802	9	1
Tyr-365	23	22	96	729	12	2